since I do seats as a learning hobby well . to make money also. I'd have you open up the seat take the cover off and hopefully the vinyl isn't too bad that it can't be stitched back together, old cars like ours still use cotton sewing thread and it rots away in decades of use. sitting actually is worse than using the seats. they may be able to "shorten" the seam a bit since it looks like it did rip the vinyl and that probably will be a problem, some backing material and canvas can "help" if you try to restitch that panel back into place (it will have to be folded over to make one panel shorter and adding backing might save it , but I 'd probable replace than torn panel with matching new vinyl if it's available
